st: gpscore for propensity score of 4 observed groups

Hi,
I have technical question regarding gpscore.
If my treatment variable is type of injury severity, what should I put for "cutpoints", "index", and "nq_gps"? The treatment level has four different levels of injury severity.
What I am seeking is to create a propensity score for the likelihood that a person develops a certain type of injury, in this case TBI, based upon a list of covariates.
This is the syntax I used for a preliminary analysis:
gpscore age child_gender prev_anxiety prev_depn prev_adhd prev_behavioral prev_other_mh, t(inj_severity) gpscore(mygps) predict(hat_inj_sev) sigma(hat_sd) cutpoints (inj_severity) index(p50) nq_gps(4)
Again, I am unsure of cutpoints, index, and nq_qps given that I have four established groups for the treatment variable.